Docker and CNCF: Making what an agent may do as portable as the agent itself
Ten years ago, the software industry faced a choice. Every vendor could ship its own image format and its own runtime, and developers would have to pick a side. Or the industry could agree on one artifact. The second option won. Docker donated its image format and the Runc runtime to the Linux Foundation, and the Open Container Initiative (OCI) formed around them. Today, a Docker image built anywhere can run anywhere. The format is the backbone of the cloud native ecosystem and a de facto standard.
Now, we see a similar problem forming around agents. There is no shared format for what an agent is allowed to do. We are proposing the same kind of answer: one artifact, built on OCI, governed in the open.
The same problem, for agents
Containers were built for immutable software. The image is the application. If you want to change it, you rebuild it, and it behaves the same way everywhere. That’s why a container image describes how software is built and says nothing about what it may do once it runs. For a web service, that was fine. It got a network and a port, and that was enough.
Agents are mutable by definition. Claude Code and Codex install packages, call APIs, and use credentials on your behalf. They change the environment they run in, and they decide what to do next. So, every team writes its own rules for what an agent may reach: a network rule here, a token there, a volume mount to get a task done. Those rules live in shell history, in dashboards, and in someone’s memory. A few months in, nobody can answer a simple question: what is this agent allowed to do?
Every team answers that on its own today, and every runtime vendor could ship its own way of answering it. That’s the kind of fragmentation OCI was created to prevent.
What we are announcing
Kits are not new. Kits have been part of Docker Sandboxes as the way you package an agent, its tools, and what it may reach into something a team can share. What’s new is the artifact. A Kit is now an ordinary OCI image, and the format that describes it is open.
Today at WeAreDevelopers, we announced the Docker Sandbox Kit Spec, open source under Apache 2.0. A Kit carries three things in one image: the agent, its tools, and a typed list of everything it asks to reach, such as hosts, credentials, and volumes. Because the list is part of the image, pinning the image pins the agent and its requests together.
A Kit is not a new artifact type and not a fork of any OCI specification. It uses an extension point OCI already defines. It builds, pushes, pulls, signs, and scans like any image you run today, because it is one.
Today, we’re bringing the spec to CNCF, under their neutral governance, just like we did when the image format went to OCI.
Why it matters
Adoption is free. Because a Kit is an OCI image, every registry, scanner, and signing tool you already run handles it. There is nothing new to deploy.
The answer travels with the agent. Because the requests are in the image, “what may this agent do” has one answer. A teammate can pull it. A reviewer can diff it. A conforming runtime can enforce it. When a new version asks for more, the change shows up as added lines someone can refuse.
An ecosystem, not a format
Docker has always had an ecosystem-first mindset. The Dockerfile mattered because anyone could write one, any registry could store the result, and any runtime could run it. Kits follow the same approach, and we did not build them alone.
We have worked with AWS, Box, Datadog, Dynatrace, JFrog, NanoClaw, OpenClaw, Palo Alto Networks, Snyk, and more to build Kits for their tools. Cloud platforms, observability, security, artifact management, content, and agent frameworks are all represented. The Kits we unveiled during the opening keynote at WeAreDevelopers today are the product of all that work, and they are the first of many.
MCP gave agents a standard way to talk to a tool. Kits give the ecosystem a standard way to publish the whole arrangement: the agent, its tools, and what it asks to reach, in one image anyone can pull. That’s what turns a format into a supply chain. For example, a database vendor can publish a Kit that connects any agent to its service with the scope it recommends.An agent maker publishes its own Kit, so the request list comes from the people who built the agent. A platform team publishes one for the company, and every engineer starts from the same place.
None of that happens if the format belongs to one vendor. A standard for deciding what an agent may do is worth a good deal less if it belongs to whoever sells you the runtime. Docker Sandboxes is the first runtime that enforces it. It should not be the only one, and under CNCF governance, it will not be.
Containers made software portable. Kits make authority portable: the set of things you deliberately hand over to an agent travels with the agent, in the same image, and means the same thing wherever a conforming runtime opens it.
“Standards are what let an ecosystem move fast without fragmenting, and few companies understand that better than Docker. By delivering Sandbox Kits as standard OCI images, Docker is giving the industry an open, repeatable way to package an AI agent, its tools, and its guardrails as one artifact. OCI is the foundation the cloud native ecosystem is built on, so a standard for agents that builds on OCI reaches the whole ecosystem at once. The CNCF welcomes this, and we’re excited to work with Docker and the community on making it broadly adopted.“
Chris Aniszczyk
CTO at CNCF
Build a Kit
If you make a tool agents use, publish a Kit for it. If you run agents, start from one and share it with your team. The specification, the capability pages, and a worked tour of a real Kit are at docker/sandbox-kit-spec. If there is a Kit you cannot express, or a rule a runtime cannot implement, open an issue. Every Kit published and every issue filed is how a standard gets built.
